The atomically sharp edges of graphene can act as surprisingly efficient electronic tweezers to trap molecules and nanoparticles. This is the new finding from researchers in the US and the UK who say that the mechanism of action of the devices will allow them to precisely position molecules along the edges of a graphene sample and then probe these molecules using other sensors or even graphene itself. The tweezers, which work thanks to dielectrophoresis, operate at voltages as low as 0.45 V and can pick up objects like nanodiamonds, nanobeads and DNA from solution within seconds. The devices might be used to make handheld disease diagnostic systems and to study the biophysics of single molecules.
Graphene is a sheet of carbon atoms just one atom thick that has many unique properties, including the fact that its optical, electrical and plasmonic properties can be tuned. These make it ideal for applications such as biosensing.
The researchers, led by Sang-Hyun Oh of the University of Minnesota at Minneapolis, made their tweezers by sandwiching an 8 nm-thick hafnium oxide (HfO2) dielectric layer between single-layer graphene, grown in a process called chemical vapour deposition, and a metal layer. HfO2 is an insulating material commonly employed in microelectronics.
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